It’s primarily used as a guardrail at special trackwork frog locations. Also used as restraining rail on curved tracks, and most recently included in a new design of switch point guard.
The major advantage of 33C1 section as a guard/restraining rail is the capability of independent mounting from the running rail.
It can be a bolted or boltless design. In a bolted design the 33C1 section is fastened to the support chair/bracket. In a boltless configuration, the 33C1 profile is fastened with e-clips.
To improve on its function as a restraining rail, the 33C1 section can feature a raised design to allow additional contact with the flat vertical face of the back of wheel, or it can be designed flat so as not to interfere with snow removal equipment.
The 33C1 restraining rail assembly provides for flangeway with adjustment by adding shims directly behind the restraining rail. This adjustment can be provided without disturbing the running rail installation.